The present proposal is designed to study the lymphocyte subpopulations in the uremic experimental animal model and to determine how the acute and chronic uremic states affect their immunological function. Suppression delayed hypersensitivity in the acute uremic state suggests that the cells involved in cellular immunity, T lymphocytes and macrophages, are defective. These two cell populations will be further studied in the uremic animal model and their functions in such responses as antigen specific lymphocyte proliferation, mixed lymphocyte reaction, cell mediated lympholysis and helper activity will be studied and compared with lymphocytes of normal sham operated aaimals. Since the major cause of death in uremic patients is infection, this study is of importance since it aims to pinpoint the defective cell or cells which in turn might lead to a correction of the defect. In addition, by means of in vitro assays, we will be able to determine the effect of uremic serum factor(s) and screen potential toxins that are known to be elevated in uremia. In summary, the primary emphasis of this proposal is to study and define the response of immunologically reactive T cells and macrophages in renal failure.